Lucas was born to Cheryl Stansbury and mobster Julian Jerome. But Cheryl had been told her baby had died when she emerged from the anesthesia. In truth, Lucas was sold to Bobbie Spencer Jones, who was driven to desperation when her planned legal adoption fell through at the last minute. Bobbie named the baby Lucas for her own brother, Luke Spencer.
In 1990, baby Lucas fell ill and was diagnosed with juvenile diabetes. Bobbie, unbeknownst to her new husband, Tony, worried that she knew so little about Lucas's medical background. She worried more when she saw Cheryl bonding with Lucas. Cheryl mentioned that Lucas looked like the child she and Robert Scorpio might have had, and Bobbie's investigation afterward turned up proof that Lucas was! Meanwhile, Cheryl remembered hearing her baby cry and knew that her baby hadn't died. Cheryl's sister, Tiffany Hill, thought the baby might have been Julian Jerome's and Cheryl let Robert believe her baby was Julian's when she asked Robert to find the child.
In 1991, Robert uncovered the truth about Bobbie buying Lucas and stopped Bobbie's last-ditch effort to flee Port Charles with the son she loved with all her heart. Tony was devastated by the truth about Lucas, took their daughter, B.J., and left Bobbie. Bobbie had also lost her friends, Robert and Tiffany, over her deceit. Robert returned the child to Cheryl, who revealed that Robert was Lucas's biological father. However, paternity tests proved Robert wasn't his father. Cheryl and Lucas moved away from Port Charles, and in time, Bobbie and Tony reunited.
By the following year, Cheryl died in a car accident and Tiffany and her husband, Sean, brought Lucas back to Port Charles to live with them. Tiffany had tried for months to conceive a child with Sean, but to no avail. But Cheryl's will had left Lucas's care to Bobbie and Tony, because Cheryl thought Tiffany didn't want any children!
Bobbie and Tony were thrilled to have Lucas back in their family, but Tiffany was bitter and vowed to fight Cheryl's will. Tiffany pulled out all the stops to gain custody of Lucas, even exposing Bobbie's past as a prostitute. Sean was disgusted with the lengths Tiffany went to in order to obtain custody of Lucas and refused to testify, which led custody of Lucas being granted to Bobbie and Tony.
In 1994, Lucas was trying to comprehend his cousin Maxie's heart disease when the Jones family was dealt another crushing blow. B.J. Jones, Lucas's sister, was rendered brain-dead in a school bus accident. Tony made the difficult decision to donate B.J.'s heart to Maxie, and Tony and Bobbie explained to Lucas that B.J. was going to live in Heaven.
By 1996, Lucas had come to terms with Bobbie and Tony's divorce, which was a long time coming.
Lucas fell deathly ill in 2001, when Helena Cassadine's master plan came to fruition. Helena had Lucky poison Lucas with a deadly bio-toxin and Helena offered Tony the cure if he would help her with her diabolical scheme. Tony agreed and discovered that Helena had a secret lab thirty flights below the sub-basement of General Hospital. In the lab was Helena's "dead" and cryogenically-frozen son, Stavros. Tony defrosted him and brought him back to life. Fortunately, Tony eventually told Luke of Helena's plot just in time for Luke and company to shut down Helena's operations for good. Luke was able to retrieve the cure for Lucas's mysterious illness, and Lucas made a strong recovery.
In 2002, Lucas was doing poorly in school. Lucas confessed to Maxie and Georgie Jones that he had trouble concentrating when he tried to study. Georgie determined that Lucas had a learning disability. While working overtime to help Lucas with his studies, Georgie developed a crush on Lucas! Unfortunately for Georgie, Lucas had developed a crush of his own -- on Maxie!
Maxie used Lucas's invite to Kyle's party to get close to Kyle. Maxie caught Kyle's attention and they went to his bedroom, but Maxie couldn't go through with sleeping with him just to get herself in with the cool crowd. But that didn't stop Kyle from spreading lies about their wild night together! Maxie's reputation was ruined! Lucas decided to trip Kyle up by telling him that Maxie was pregnant and Kyle was the father. Kyle admitted that he never slept with Maxie and Maxie was grateful to Lucas for salvaging her reputation.
When Maxie and Lucas were throwing a party at the Jones house while Felicia was out of town, Georgie wanted to come, but Maxie and Lucas wouldn't let her. Georgie pretended she had a date and hid out at Kelly's. When Lucas and Maxie were coming, Georgie grabbed the nearest teenage guy and kissed him, not realizing he was worldly young Dillon Quartermaine!
As Georgie and Dillon began hanging out together, Maxie and Lucas began to worry that Dillon was nothing but bad news for Georgie. But Lucas's attention was soon back on Maxie. He was astonished that she still felt Kyle was her ticket to being in the cool crowd. Even after Kyle humiliated Maxie by broadcasting their night in bed together on the Internet, Maxie forgave Kyle. Lucas was baffled as to how Maxie was so blind to who Kyle really was. In turn, Lucas turned his attentions toward Georgie, knowing Georgie was more willing to receive them. Georgie was thrilled to be Lucas's focus for once, and she herself was blind to Dillon's growing feelings for her. When Maxie found out that Georgie had rented a hotel room for after prom with the intent of sleeping with Lucas, Maxie got Dillon to help her trick Georgie into seeing Maxie and Lucas making out. Georgie was hurt and angry and vowed never to forgive any of them. Lucas went away for awhile and returned older and more handsome. He went to Kelly's to look for Georgie and literally ran into Brook Lynn Ashton as she was storming off following an argument with Georgie. After a brief conversation with her, he reunited with Georgie, who revealed that he'd been away at boarding school for the past year. Dillon was jealous at Georgie's closeness with Lucas, but they worked past it.
After several talks with Brook Lynn, one of which was about her life on tour with her mother, Lois Cerullo, Lucas began slowly developing feelings for her. He was intrigued by her desperation to reunite her mother with her father, Ned Ashton. He clearly saw this when she joined a girl band competition her mother entered them in just so she could keep her from seeing local mobster Lorenzo Alcazar.
Georgie had Lucas help her teach Dillon a lesson following a fight about women being treated like sex objects. She asked Lucas to hit on Dillon while he was dressed in drag for his part in an all-girl singing group. But Brook Lynn saved Dillon and berated Lucas for what he did to Dillon. Lucas defended his actions, saying he'd do anything for Georgie. Some time after that, Lucas hit on Dillon a second time at Georgie's urging, but after Dillon punched him for coming on too strong and revealing that he was a boy right after that, Lucas admitted that he had been asked by Georgie to do that. Dillon yelled at Georgie for humiliating him and broke up with her. However, Georgie was slow in learning her lesson. She convinced Lucas to kiss her while Dillon and Brook Lynn watched through the window at Kelly's. But Brook Lynn and Dillon knew of the plan ahead of time and they refused to date Georgie and Lucas. However, Lucas and Brook Lynn grew close during a scary night at the Quartermaine Mansion involving a sťance, a killer, and two murders. He saw Brook Lynn's uniqueness and comforted her when she tried to blame herself for all the horrors of the evening.
When Brook Lynn got a makeover for her new singing career, she hated it until Lucas complimented her. He asked her to dance and they shared their first kiss.
In 2006, Lucas "came out" to his friends and parents. His friends supported him, and although Bobbie defended him to Tracy, her first instinct was to get him counseling. When he told his father, Tony, he was shocked by how easily his father accepted it. A few months later Tony died unexpectedly from an epidemic outbreak and Lucas mourned the loss of his father. After his father's death, Lucas moved to Seattle and Bobbie moved there as well a few years later.
Lucas returned to Port Charles to be with his mother after Carly went missing. He ran into his other sister Sam Morgan and his biological father Julian Jerome. Lucas was shocked to discover that Julian was alive and wondered why his mother had not told him. As Lucas digested the news, he met General Hospital lab technician Brad Cooper and Brad shared that though he had been raised by adoptive parents, his biological father was the former organized crime figure Kim Wu. Lucas was surprised by how much he and Brad had in common and they spent the night together. The next day, Lucas let Brad know that he was interested in pursuing what they might have despite Brad's attraction to a man named Felix.